This invention relates to sanding devices and in particular to a pad assembly for a rotary disc sander of the vacuum type.
In my U.S. Pat. No. 4,058,936 issued Nov. 22, 1977, I have described several embodiments of a vacuum sanding device of the double-acting type. The present invention is directed specifically to a pad assembly for a rotary vacuum operated disc sander but the means for driving the disc and the vacuum creating means for the disc assembly may be the same as that in U.S. Pat. No. 4,058,936.
Rotary sanding devices revolve at fairly high speeds and are used in grinding operations and heavy duty forms of work such as automobile bodies etc. Due to the nature of the work and the varied materials to be sanded or ground, it has until this time been difficult to obtain an efficient rotary sanding assembly having an attached vacuum arrangement. This is mainly due to the fact that the ground particles clog up small passages in the disc, particularly when the pad is flexed under pressure.
The present invention overcomes the deficiencies of the prior art by providing a vacuum rotary sander with a flexible pad body that is secured to a rigid head member which in turn is connectable to a pneumatic rotating device as described in U.S. Pat. No. 4,058,936. Additionally, the rigid head may be enclosed by a vacuum housing such as that shown in U.S. Pat. No. 4,058,936 whereby the particles ground by the pad assembly are quickly and efficiently carried away from the unit. A plurality of apertures in the head communicate with other apertures in the lower surface of the pad by way of internal channels in the pad body and these channels are angled toward the direction of rotation of the pad so that there is a leading action to the vacuum function applied to the apertures when the pad is being rotated. Apertures in the lower portion of the pad coincide with apertures in an abrasive disc which is removably secured to the assembly and, in a preferable form, the apertures in the lower part of the pad are elongated in the direction opposite to that of rotation so as to allow some slippage of the abrasive disc relative to the pad assembly without losing alignment of the apertures in either member.